Appendix A Calibration - Measurement Computing PML 1000 Operating Instructions Manual

PML 1000 Operating Instructions
Analog Output
Ranges
Accuracy
Temperature drift
Output Ripple
Response
Resolution
Maximum output
Isolation
Communications Interface
Type
Display Type
Range

APPENDIX A CALIBRATION

Introduction
This appendix describes the steps necessary to calibrate your LVDT to your PML 1000 in more detail.
Initial Set-up
The LVDT should be connected to your PML 1000 as described earlier in this manual and the appropriate input
measurement mode selected from the input menu. You should also set up the correct excitation voltage and
frequency for your LVDT, as described in the documentation supplied with your LVDT. The PML 1000 uses
different amplification gains depending on the output of your LVDT. In order for the PML 1000 to set the correct
gain for your LVDT, you need to set the LVDT sensitivity and stroke values in the input menu. If you are unsure
of the characteristics of your LVDT then you should select the Automatic Gain selection option from the input
menu and set this to ON.
Null Position Locator
It is important that the LVDT operates around the midpoint of its stroke as this gives the best results by
minimizing any errors due to non-linearity. A feature of this PML 1000 is the ability to locate the midpoint of the
LVDTs measurement range (Null point). To do this select NULL from the main menu and a value will be
displayed (flashing). The nearer the value to zero the nearer the LVDT is to its null position. The LVDT should
be mounted so that the required measurement range is equally divided by the Null position.
Initial Calibration
To perform an initial calibration of the LVDT to the PML 1000 select the CAL option from the main menu. The
display will show the message L-iP (low input). Set the position of the LVDT to its minimum displacement
position (minimum stroke) and note the displacement i.e. 0mm. When the LVDT is set at its low calibration point
press the Enter key, the display will show Wait while the PML 1000 measures the output from the LVDT. This
takes a few seconds. When finished the display will show H-iP this indicates that the PML 1000 is ready to
calibrate the high point. Set the LVDT to its high calibration point maximum displacement position i.e. 200mm.
Press enter when ready to continue and the unit will display the message WAit while it is measuring the output
from the LVDT. At the end of the calibration sequence the PML 1000 will use the two measured output values
from the LVDT to calculate its own calibration constants which it will utilize in all future measurements. Note
these constants are all retained when power is removed from the PML 1000. When a calibration is performed
with the Automatic Gain selection enabled the PML 1000 will determine the optimum internal gain setting for all
future measurements from the output levels from the LVDT detected during calibration.
APP-01025, Rev A
PML 1000 Operating Instructions
0-10V, 0-20mA or 4-20mA selectable
0.2% of span
< 100ppm/°C
< 10mV or50mA @ 30Hz
63% within 32mS
99% within lOOmS
0.05% of span, 5mV or 0.01mA
18V @ 25mA
500V
EIA RS485 (RS 422 Compatible)
0.56" High brightness 7 segment LED red (Optionally green)
-19999 to +99999
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